Oil cooler for aircraft



O;t.16,1945.l l 'B .BURNS R 2,387,057

OIL COOLER FOR AIRCRAFT Oct. 16, 1945.

E. BURNS* OIL COOLER FOR AIRCRAFT Filed Jan. 25, 1943 6 Sheets-Sheet 2 Smulutor.: 5m/ c5 SUR/ys.,

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B. BURNS Filed Jan. 25, 1945 OIL COOLER FOR AIRCRAFT Oct. 16, 1945.

m mw .lllllllu Gttorneg .A

Oct 16, 1945. B. BURNS 2,387,057

OIL COOLER FOR AIRCRAFT Filed Jan. 25, 1943 e sheets-Sheet 4 SnDcntor g Ha/x5,

orme, 1945. B. BURNS 2,387,057

OIL COOLER FOR AIRCRAFT Bnventor;

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' :inventor:

l f I I 7 74 7781 7o Bg 9m/C5 5g Si Gttorneg Patentecl Oct. 16, 1945 UNITED STATES OIL COOLER FOR AIRCRAFT Bruce Burns, Los Angeles, Calif., assignor to The Garrett Corporation, Airesearch Manufacturing Company division, poration of California glos Angeles, Calif., a cor- Application January 25, 1943, Serial N0. 473,544

' 4 Claims. (Cl. 257-128) My invention relates in ,general to cooling devices, and relates in particular to a cooler for use in aircraft to cool engine oil.

In general, the objects of my invention include the provision of a cooler capable of sustaining high `internal pressure, having high cooling einciency, and having large capacity with respect to its height, In order that they may have maximum strength against the bursting eiect ofhigh internal pressures, oil coolers extensively employed in aircraft have been made cylindric in form, and the capacity or cross sectional area of a cooler employed in a .given aircraft has been limited in many instances by the vertical dimension of the wing space to receive the cooler. In

my present invention I provide a cooler which is.

horizontally elongated and Atherefore* provided with increased capacity for a given height as determined by the vertical dimension ofthe airpl'ane wing space which is to receive the cooler.

It is an object of the invention to provide a cooler which is elongated in cross section .and has reenforcing means .acting in tension along the minor axis thereof. and which has means acting along its major axis to take compressive stresses,

' a cooler comprising a core and a shell with means connecting the core and the shell in a manner to compensate for differences in expansion and contraction of the shell and the core.

v A further object ofthe invention is to provide new and improved inlet and outletl ttings fora floads which are applied as the result of fluid pressure within the cooler acting outward against the.

walls of the shell so as to stress the same in tension.

It is a further object of the invention to provvide a cooler and a valve mechanism associated with the external walls curved inv characteristic 1' manner so as to act in tension in response to pressure built up within the cooler.

A further object of the invention is to provide a cooler of elongated cross section having inlet and outlet means `disposed in positions offset to the side of the cooler and in such manner that they do not add to the vertical height of the cooler assembly.

A further object of the invention is to provide a cooler of elongated cross section having inlet and outlet means in endrelation thereto, with provision for iiow of the oil to be cooled in a di-4 rection substantially parallel to the major axisv of the cooler. v Y i A further object oi the invention is to provide an oil cooler .of elongated form having a major plane lying along its major axis and a minor plane lying along its minor axis, with. an external wall consisting of wall sectionswhich curve voutward and extend from the minor plane to the major plane so as to form two somewhat elliptical lobes joined together at the minor plane.

A- further object of the invention is to provide a cooling device having .a novel form of bypass means capable ofV withstanding extremely high pressure and shock loads, and having means for protecting the core of the cooling device against excessive pressures.

A further object -of the invention is to provide with the cooler so as to be connected to the cooler in a number of diierent arrangements to enable use of the cooler in various positions and with inlet and outlet pipes of the cooler in a variety of positions,

Further objects andadvantages of the invention will be brought out in the following part of the specification.

Referring to the drawingsvwhich are for illus- I 3--3 of Fig. 1.

Fig. 4'is an enlarged lfragmentary sectional view of the central portion of the cooler taken along the line 4-4 of Fig'. 2, with the upper and lower portions thereof moved inward.

Fig. fia. is a, fragmentary sectional view of the leftward extremity of the cooler, taken also on the line 4 4 so as to cooperate Awith the fragmentary sectional View Fig. 4.

Fig, 5 is a similar view taken along the line `5--5 i ofFig. 2.,

Fig. 6 is a sectional elevation taken along the lineG-B ofFig. 1.

Fig. 7 is an enlarged lfragmentary sectional K view taken as indicated by the line 1 -Tof Fig.

5 to show the breather 8. Y

Fig. 8 is an enlarged fragmentary` sectional view taken as indicatedby the line 8-8 of Fig. 4 to show the breather v9.

Fig. 9 is a fragmentary view .similar to Fig. '74

stantially elliptical in shape and being symmetrical about a major axis A-A and a minor axis B-B, the core and shell thus having substantially two portions or lobes on opposite sides of minor axis B-B. The core 2 comprises a plurality of open end tubes 3 having hexagonal shaped ends 4 which are enlarged and are mutuallyvcontiguous and secured together as by soldering or the like and substantially form end walls for the oil cooling chambers within the shell l, there being spaces between the tubes which permit a flow of oil across and between the tubes' within the shell I. The core 2 is dividedintofoursections,

r4plates l35 are secured to the edges of the outer namely, the upper core sections2a` and 2b and' the lower core sections 2c and2d. A plurality of warm-up and bypass tubes extend crosswise of and between the upper and; lower groups of f cooler. around the end portions of the shell to the pointsl 8b in the bottom or the cooler, and are secured as by soldering to the perimetral portions of the tube ends 4. AI pair of shorter breathers 9 placed respectively at the top and bottom of the cooler overlap the ends of breather members 8 andare soldered to them and engaged to the ends 4 of perimetral tubes 3. The upper and lower core sections are secured to a pair of center breathers I0 as by soldering of the tube ends 4 thereto. The ends 4 of the tubes 310i .the core sections adjacentv and on opposite sides of the axis B-B are similarly secured to pairs of vertical channels II, the inner ends of which are vsecured to the center breathers Iil and the outer ends-are "secured to small breathers 9. Expansion of the shell and core'substantia-lly along the axis B--B is prevented by a plurality of tie rods I 2, spaced along' the axisB-B as shown in Figs. 2, 3, and 4. Tie rods I2 are provided with suitable securing nuts I3 and anged washers or eyelets I4 which are seated in` openings in the shell I as shown in -`Fig. 4. The center breathers Iare each provided with outer flanges I 5l to which tube ends 4 are soldered and a flexible channel portion I6 which permits the breathing action or expansion and. contraction due to changes inV temperature during Ydifferent operating conditions.

The shell l comprises upper and lower outer plate members Il which are corrugated or channeled, as at I8, to provide-augmented surface area, the plates I'I being each secured to an 4inner shell plate I9, the .ends of the upper and lower platesl91overlapping the plates 29 .which extend across Vthe'major axis A-A, wherebyT Vthey are securedat, one end to a manifold I and at -the other-end to a manifold 6. 1

.Al pair of end plates 2| as Shown in Fig. .5, are secured to and overlap adjacent end portions of thejplatesY I9.Y A pair of plates 22 areprovided and each is secured to one of the plates I9 and `shell plates I'I, as shown in Figs. 4 and 8.

f As shown in Fig. 3, a plurality of spacers or filler strips 36 are positioned between the tubes 5 so as to forma baffle therewith and additional spacers 3T are provided between outermost tubes 5 and the walls formed by end portions 4 of the `v tubes 3. The central spacer 36, indicated by the numeral 36 is positioned between the central pair of tubes 5 and is provided with a plurality of apertures 39 aligned with apertures 40 in the adjacent tubes to provide a warm-up flow of oil therebetween, as will be explained hereinafter.

Return manifold 1 has a return flow chamber 4I and a plurality. of ns 42 which extend outwardly from the wall 43 of the manifold 'I and form therebetween vertical flow passages 42' for the oil. A wall 44, A1ig.,6, is formed in theterminal manifold 6, forming an inlet chamber 45 and an outlet chamber 46 therein. The manifold B is provided with lower and upper threaded openings 48 and 49 for the chamber 45, to which are secured flanged bushings 50 and 5I, to the A opposite ends of which are secured tubular memprovided with a plurality of ilanged openings 23'which are aligned withsimilar openings in the plates I9. As shown in Fig. '7. the breathers 8.are-each formed with an inner ange 25, to which the perimetrical tube ends 4 .are secured, an. outer flange 26,.and anexible web 21. The flanges 26 of the breathers 8 areconnected to bers 52 and 53 which extend' through ilanged openings 23 in the plates 22 and openings in the shell plate I9. The manifold 6 is .also provided with lower and upper threaded openings 54 and 55 for the chamber 46, to which are secured flanged bushings 56 and 51, the outer ends of which are secured to tubular members v58 and 59, which extend through additional openings 23 in the other plate 22. Additional tubular members 60 and 6I are provided which extend through plates I9 and 22, as shown. amounting plate 62 is provided with apertures and is suitably secured to the ends of tubular members 52, 58, and 60, and an inlet manifold 63 is suitably secured to the plate 62 and is provided with an inlet chamber 64 and an inlet opening 65, and an inlet pipe 66 may be suitably secured thereto.

The chamber G4 has an outlet opening 61 in communication with tubular member 52. The manifold 63 has a wall B8 and a wall B9 forming a chamber V10 which is in communication with the tubular member B0. Walls 68 and 69' are provided with openings to receive a valve casing 'II which hasa valve seat 12 inthe chamber 64 and a plurality of apertures 'I3 in communication with the chamber 10. The manifold 83 is provided vwith a threaded counterbore I4 for threaded engagementwith a valve stem guide member 15, whichalso forms va closure for the end of the valve casing 1I. The member 'I5 is provided with a bore 'IB to receive the end of a valve stem I1 which is provided with a valve closure 'IB for the valve seat 12. A disc 19 is secured to the valve stem 'Il and provides a seat for a packing ring 89 which is held thereagainst by a flanged retaining disc BI, and a spring'82 is secured between the member 'I5 and the retainer 8| to normally bias valve 'I8 in open position, a resilient expansion ring 83 being suitably secured in a groove in the casing .'II to provide a seat for the disc 13, and retain the valve closure assembly within the valve casing. An aperture 34 isprovided in the guide member 15 and ,permits the expulsion of air from the interior of the casing l l so that the valve 'la may be closed quickly upon a fluid pressure surge in the chamber 64 from the inlet B6 acting leftward against the disc or piston 19.

` A mounting plate 85, substantially similar to the plate 62, is provided for and secured to tubular members 53, 59, and 6|, and an outlet manifold 85 is securedthereto. The manifold 85 is provided with a plurality of valve seats 81, B8, and 89 and has a chamber 98 in which are positioned valve closures 9|, 92, and 93 for the Valve seats 8l, 88, and 89. The manifold 86 is provided with threaded openings 94, 95, and 96 to receive the1threaded closures 91, 98, and 99, the closures 9'! and 98l securing vvalve guide rods |90 and IUI respectively, for the tubular stems of a pressure relief or bypass valve 9| and a check Valve 92. A spring |92 is positioned between the closures 9| and 9'! and a spring |93 is positioned between the closures 92 and 98, the spring |02 being substantially stiifer than the spring |03, the effect of which is that the closure 9| will be in closed position during normal operation under a pressure insucient to open the bypass valve 9|. The valve closure 93 is secured'to a thermo-responsive mounting |84, such, for example, as a uid filled bellows, secured to the closure 99 so constructed that the closure 93 will be in open position at relatively low temperatures and closed at a Arelatively higher predetermined temperature.

In the operation ofthe invention, the oil to be cooled enters under pressure from the inlet pipe B into vthe chamber B4 and during normal operationit is conducted past the valve into the chamber 'I9 and through the tubular member 69 into the lower portion of the core 2. It thereupon passes over and under the tubes 3 under the baffle provided by the tubes 5 and spacers 36,31, and 38, and upwardlly through the spaces 42 between the fins 52 and thence in a reverse direction throughthe upper portion of the core 2 and out through the tubular member 6| past the valve 92 into the chamber 99 and out through the outlet pipe |05. Under these conditions, the valve closures 9| and 93 Will be in closed position.

During the initial operation of the cooler and whenever the operating conditions thereof are at low temperatures such that the thermostatically controlled valve 93 is open and the viscosity of the oil is relatively low so that there is considerable back pressure due to fluid friction in the passages between the tubes 3, a flow of oil will occur from the chamber 54 through the tubular member 52 and the fitting 59 into the chamber 45 of the manifold 5. If the valve 9| is closed and the fluid pressure is not sulficient to open this valve, the flow will be through the tubes 5 leading from the chamber (l5 to the chamber 4| of the manifold l and return through the tubes 5 which communicate with the chamber 45 of the manifold 5. The flow will thereupon be upwardly through the fitting 5l and the tubular member 59 into the chamber 99 past the valve 93 which, as stated above, will be in open position and the flow is thence out through the outlet |95. The flow of warm or hot oil through the tubes 5 will warm up the adjacent oil in the cooler core 2 to reduce the viscosity thereof so that a normal flow through the cooler will be established. Some of the flow of warm oil from the innermost tube 5, leading from the cham- Cil ber 45, will pass into the adjacent tube 5 which leads into the chamber 46 through the apertures 4|] therein and apertures 39 in the spacer 38: In this manner a short warm-up bypass is provided for the oil. If the backfpressure through'the bypass tubes 5 is relatively high due to low temperature of the oil therein, a bypass ow of oil will occur from the chamber 45 through the fitting 5| rand the tubular member 53 past the valve 9| into the chamber 90, since the valve 9| will be unseated by such pressure. This valve 9| will again seat when the back pressure in the'chamber 45 of the manifold 6 drops to the valve closing pressure determined by the spring |02.

The construction of the cooler as described, being elliptical and having a major axis dimension substantially greater than that of the minor axis dimension, permits `the placing of the cooler in limited spaces such as within the wings of an aircraft. It will be observed that the extreme dimensions of manifolds 63 and 86 are substantially within the limits of the dimension along the minor axis B. Manifolds l63 and 85are such as to be reversible end for end on mounting plates 62 and 85 which may be desirable if either or both inlet and outlet pipes 66 and |95 are to be provided at the opposite side from that shown. Also, these manifolds are interchangeable since the spacing of the tubular members 52, 53, 58, 59, 60, and 6| are uniform. The mounting plates 82 and 85 are similar, but only ve of the six outlets therein are employed at'any one time. For example, it will be noted that when the manifold 64 is arranged as shown in Fig. 6, the lower end of tubular member 58 is closed by the wall 64 of the manifoldA 64. If the inlet pipe 66 is on the opposite side of the cooler, the manifold 54 will be turned end for end so that the inlet port 51 will communicate with the lower end of the tubular member 58, and the wall 64' will then close the lower end of the tubular member 52. if this is done, it will be necessary to interchange' the Valves 9| and 93 so that the bypass valve 9| will be aligned with the port 57 of the manifold 64 in its new position. This may be accomplished by turning the manifold 85 end for end or moving the valve Bland its associated closure 9'! to the position of the valve 93 and its associated thermostat |04 and closure 99, the valve 93 then being placed in the position of the valve 9|, without changing the position of the manifold 85.

The shell I of the cooler comprises a unit capable of withstanding an internal pressure considerably greater than that to which it is normally subjected in the oil circulating system. Should there be a heavy oil surge, or should restriction of the flow of oil through the return pipe |95, Fig. 6, cause a build-up of pressure in excess of the maximum normal pressure for which the cooler is designed, the auxiliary core protecting valve 18 will close against the seat 12 in the manner previously described, and should there be a reverse surge through the return piping |05, the check valve 92 will prevent a reverse flow of oil from the chamber 98 through the tubular member 6| into the core of the cooler.

Vertical expansion of the shell due to oil pressure therein is prevented by the tie rods l2 which act in tension. Outward pressure against the walls of the shell between the ends of the tie rods and the manifolds 6 and '1 results in tension in the side walls and inward pressure against the manifolds 6 and 1, inward movement of which is prevented by the intercommunicating tubes 5 which are placed in compression. As shown in Fig. 1, the Walls of the shell extend from the points X near the plane B--B to the points y at the extreme sides of the cooler through arcs, each of which has a single radius R; Accordingly, the four sections X-Y of the cooler shell comprise cylindrical segments, each of which are placed in tension when pressure is applied internally to the cooler, but which are so formed and supported that Warpage or material change in curvature will not occur therein.` The core 2 may be regarded as floatingly supported within the shell by the breather members 8 and 9 so that relative Vexpansion and contraction of the core may occur without injury to the structureel' joints between the cooperating parts. I

The alternative form ofrbreather lilas shown in Fig. 9, comprises a metal wall Ill shaped so as to have the form of a channel, this channelhaving substantially parallel side Walls H2 and H3 adapted to be secured to the core 2 and the outer wall or shell of the cooler, including the wall 20. The breather wall I l I has an interconnecting portion H4 in the form of a reverse 'bend in a position offset toward the coreZ so as to have'a partial overhanging relation to the periphery of the core 2.

I claim as my invention:

1. In yfluid cooling means, the 'combination of:

an oval core; an oval shell for vsaid core having fluid inlet and outlet means; a'unitary'baiile and' bypass means in said shell comprising a plurality of forward and return ducts extending across theV interior of said core in a plane coinciding with the major axis of the shell, spacers between said ducts, and manifold 'means for the ends of said ducts, said manifold means being connected'to said shell so that said baille and bypass means will resist longitudinal contraction `'of said shell; 'and means to connect at least one of said manifold means with said inlet and outlet means. f

2. In a cooler of the character described having a core dening passages for a iiuid and a coolant, the combination of a shell to contain said core comprising upper and lower walls disposed above and below a longitudinal plane, a'compression member extending along said longitudinal plane from end to end of said shell,` said compression member comprising a plurality of longitudinal ducts and manifolds at the ends of said compression member communicating with said ducts and being connected to the ends of said upper and lower wall members, one of said manifolds having Yported inlet and outlet chambers therein respectively connected to the near ends of different ducts of Ysaid compression member and the other of said manifolds having a passage connecting the other ends of said different ducts and said diiferent ducts having therebetweena number of small intercommuncating passages spaced along the length thereof, tension means extending through said shell in a transverse plane in crossing relation to said longitudinal plane, said tension means being shorter than said compression member and being connected to the intermediate portions of the upper and lower walls, said upper and lower walls converging toward the end of said compression member and being each convexly curved from a position adjacent said transverse plane toward the ends of said compression member; and means connecting the edge portions of said upper and lower walls to said core.

3. In a uid cooler, the combination of: an oval core; an oval shell for said core having iiuid inlet and outlet means; means including a plurality of forward and return ducts extending across the interior of said core, longitudinally thereof, in a plane coincident with the major axis of the shell and manifolds at the respective ends of said ducts for bypassing fluid from said inlet to said outlet; and means joining said ducts to each other and to the walls of the core to constitute a baille for separating theV spaceY Within the core into a plurality of compartments, said baille and bypass means, including said manifold, being interposed between the end portions of said shell in compression resisting engagement therewith to constitute a strut for resisting deformation of said shell under the expansive force of fluid passing through said core.

4. A cooler as dened in-claim 3, wherein said core includes peripheral core wall members spaced 

